1. Field of Invention
The present invention relates to wireless network communication and more particularly to a method and apparatus for providing a mobile terminal with a technique to detect whether a power save mode of an access point (AP) servicing the mobile terminal is working properly.
2. Description of Related Art
Modern society has quickly adopted, and become reliant upon, handheld devices for wireless communication. For example, cellular telephones continue to proliferate in the global marketplace due to technological improvements in both the quality of the communication and the functionality of the devices. These wireless communication devices have become commonplace for both personal and business use, allowing users to transmit and receive voice, text and graphical data from a multitude of geographic locations. The communication networks utilized by these devices span different frequencies and cover different transmission distances, each having strengths desirable for various applications.
Cellular networks facilitate wireless communication over large geographic areas. These network technologies have commonly been divided by generations, starting in the late 1970s to early 1980s with first generation (1G) analog cellular telephones that provided baseline voice communication, to modern digital cellular telephones. GSM is an example of a widely employed 2G digital cellular network communicating in the 900 MHZ/1.8 GHZ bands in Europe and at 850 MHz and 1.9 GHZ in the United States. This network provides voice communication and also supports the transmission of textual data via the Short Messaging Service (SMS). SMS allows a WCD to transmit and receive text messages of up to 160 characters, while providing data transfer to packet networks, ISDN and POTS users at 9.6 Kbps. The Multimedia Messaging Service (MMS), an enhanced messaging system allowing for the transmission of sound, graphics and video files in addition to simple text, has also become available in certain devices. Soon emerging technologies such as Digital Video Broadcasting for Handheld Devices (DVB-H) will make streaming digital video, and other similar content, available via direct transmission to a WCD. While long-range communication networks like GSM are a well-accepted means for transmitting and receiving data, due to cost, traffic and legislative concerns, these networks may not be appropriate for all data applications.
Short-range wireless networks provide communication solutions that avoid some of the problems seen in large cellular networks. Bluetooth® is an example of a short-range wireless technology quickly gaining acceptance in the marketplace. A user does not actively instigate a Bluetooth® network. Instead, a plurality of devices within operating range of each other may automatically form a network group called a “piconet”. Any device may promote itself to the master of the piconet, allowing it to control data exchanges with up to seven “active” slaves and 255 “parked” slaves. Active slaves exchange data based on the clock timing of the master. Parked slaves monitor a beacon signal in order to stay synchronized with the master. These devices continually switch between various active communication and power saving modes in order to transmit data to other piconet members. In addition to Bluetooth® other popular short-range wireless communication techniques include wireless local area network (WLAN) communication (of which “Wi-Fi” local access points communicating in accordance with various IEEE 802.11x standards, is an example), WUSB, UWB, ZigBee (802.15.4, 802.15.4a), and UHF RFID. All of these wireless mediums have features and advantages that make them appropriate for various applications.
In recent years, WLAN technology has become very popular because of its advantage in price and bandwidth. Nowadays, WLAN is mainly used for Internet access, but real-time application like Voice over IP (VoIP) and video on demand (Vod) are identified as the future applications for wireless LAN. To support such new applications, IEEE 802.11e was standardized to define a new 802.11 medium access control (MAC) layer protocol. The IEEE 802.11e MAC is a standard to support Quality of Service (QoS), and 802.11e Hybrid Coordination Function (HCF) can support QoS in 802.11 networks. The HCF provides both a contention-based channel access, called enhanced distributed channel access (EDCA), and a controlled channel access, referred to as HCF controlled channel access (HCCA).
Handheld devices having IEEE 802.11 WLAN can provide wireless broadband access. However, since they are generally battery-powered, power consumption is a critical issue for mobile terminals equipped with IEEE 802.11 WLAN. Therefore IEEE 802.11 provides a power saving mechanism (LegacyPS) for various devices to reduce power consumption.
However, it has been noted that quite a few WLAN APs contain a broken WLAN power save (PS) implementation despite the efforts that WiFi-alliance is putting for certification. Sometimes the implementation in WLAN AP can be considered to be correct but due to the mobile device's behaviour the interoperability is still broken. Nevertheless, a non-interoperable PS operation is a major problem for mobile devices and typically it is the mobile device that gets switched to a new one and not the infrastructure.
There is only so much that an end-user can do on the mobile device to make workarounds and after that the device is basically stuck with the WLAN infrastructure behaviour forcing the end-user to disable the utilization of the PS scheme. However, a typical end-user does not have the technical knowledge of pin-pointing the problematic behaviour to WLAN PS that makes this a bad usability problem. Disabling power save permanently would result always in weakening WLAN operating times, thus it is not a solution either.
In view of this, there is a need in the art for a technique for a mobile terminal to detect whether the power save mode of a WLAN access point (AP) is working properly and react accordingly.